/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * drivers/analog/dac.c
 *
 *   Copyright (C) 2011 Li Zhuoyi. All rights reserved.
 *   Author: Li Zhuoyi <lzyy.cn@gmail.com>
 *   History: 0.1 2011-08-04 initial version
 *
 * Derived from drivers/can.c
 *
 *   Copyright (C) 2008-2009Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <semaphore.h>
#include <fcntl.h>
#include <errno.h>
#include <debug.h>

#include <tinyara/arch.h>
#include <tinyara/semaphore.h>
#include <tinyara/fs/fs.h>
#include <tinyara/analog/dac.h>

#include <arch/irq.h>

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#define HALF_SECOND_MSEC 500
#define HALF_SECOND_USEC 500000L

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int dac_open(FAR struct file *filep);
static int dac_close(FAR struct file *filep);
static ssize_t dac_read(FAR struct file *, FAR char *, size_t);
static ssize_t dac_write(FAR struct file *filep, FAR const char *buffer, size_t buflen);
static int dac_ioctl(FAR struct file *filep, int cmd, unsigned long arg);

/****************************************************************************
 * Private Data
 ****************************************************************************/

static const struct file_operations dac_fops = {
	dac_open,
	dac_close,
	dac_read,
	dac_write,
	0,
	dac_ioctl
#ifndef CONFIG_DISABLE_POLL
	, 0
#endif
};

/****************************************************************************
 * Private Functions
 ****************************************************************************/
/************************************************************************************
 * Name: dac_open
 *
 * Description:
 *   This function is called whenever the DAC device is opened.
 *
 ************************************************************************************/

static int dac_open(FAR struct file *filep)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct dac_dev_s *dev = inode->i_private;
	uint8_t tmp;
	int ret = OK;

	/* If the port is the middle of closing, wait until the close is finished */

	if (sem_wait(&dev->ad_closesem) != OK) {
		ret = -errno;
	} else {
		/* Increment the count of references to the device.  If this the first
		 * time that the driver has been opened for this device, then initialize
		 * the device.
		 */

		tmp = dev->ad_ocount + 1;
		if (tmp == 0) {
			/* More than 255 opens; uint8_t overflows to zero */

			ret = -EMFILE;
		} else {
			/* Check if this is the first time that the driver has been opened. */

			if (tmp == 1) {
				/* Yes.. perform one time hardware initialization. */

				irqstate_t flags = irqsave();
				ret = dev->ad_ops->ao_setup(dev);
				if (ret == OK) {
					/* Mark the FIFOs empty */

					dev->ad_xmit.af_head = 0;
					dev->ad_xmit.af_tail = 0;

					/* Save the new open count on success */

					dev->ad_ocount = tmp;
				}

				irqrestore(flags);
			}
		}

		sem_post(&dev->ad_closesem);
	}

	return ret;
}

/************************************************************************************
 * Name: dac_close
 *
 * Description:
 *   This routine is called when the DAC device is closed.
 *   It waits for the last remaining data to be sent.
 *
 ************************************************************************************/

static int dac_close(FAR struct file *filep)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct dac_dev_s *dev = inode->i_private;
	irqstate_t flags;
	int ret = OK;

	if (sem_wait(&dev->ad_closesem) != OK) {
		ret = -errno;
	} else {
		/* Decrement the references to the driver.  If the reference count will
		 * decrement to 0, then uninitialize the driver.
		 */

		if (dev->ad_ocount > 1) {
			dev->ad_ocount--;
			sem_post(&dev->ad_closesem);
		} else {
			/* There are no more references to the port */

			dev->ad_ocount = 0;

			/* Now we wait for the transmit FIFO to clear */

			while (dev->ad_xmit.af_head != dev->ad_xmit.af_tail) {
#ifndef CONFIG_DISABLE_SIGNALS
				usleep(HALF_SECOND_USEC);
#else
				up_mdelay(HALF_SECOND_MSEC);
#endif
			}

			/* Free the IRQ and disable the DAC device */

			flags = irqsave();	/* Disable interrupts */
			dev->ad_ops->ao_shutdown(dev);	/* Disable the DAC */
			irqrestore(flags);

			sem_post(&dev->ad_closesem);
		}
	}

	return ret;
}

/****************************************************************************
 * Name: dac_read
 ****************************************************************************/

static ssize_t dac_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
{
	return 0;
}

/************************************************************************************
 * Name: dac_xmit
 *
 * Description:
 *   Send the message at the head of the ad_xmit FIFO
 *
 * Assumptions:
 *   Called with interrupts disabled
 *
 ************************************************************************************/

static int dac_xmit(FAR struct dac_dev_s *dev)
{
	bool enable = false;
	int ret = OK;

	/* Check if the xmit FIFO is empty */

	if (dev->ad_xmit.af_head != dev->ad_xmit.af_tail) {
		/* Send the next message at the head of the FIFO */

		ret = dev->ad_ops->ao_send(dev, &dev->ad_xmit.af_buffer[dev->ad_xmit.af_head]);

		/* Make sure the TX done interrupts are enabled */

		enable = (ret == OK ? true : false);
	}

	dev->ad_ops->ao_txint(dev, enable);
	return ret;
}

/************************************************************************************
 * Name: dac_write
 ************************************************************************************/

static ssize_t dac_write(FAR struct file *filep, FAR const char *buffer, size_t buflen)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct dac_dev_s *dev = inode->i_private;
	FAR struct dac_fifo_s *fifo = &dev->ad_xmit;
	FAR struct dac_msg_s *msg;
	bool empty;
	ssize_t nsent = 0;
	irqstate_t flags;
	int nexttail;
	int msglen;
	int ret = 0;

	/* Interrupts must disabled throughout the following */

	flags = irqsave();

	/* Check if the TX FIFO was empty when we started.  That is a clue that we have
	 * to kick off a new TX sequence.
	 */

	empty = (fifo->af_head == fifo->af_tail);

	/* Add the messages to the FIFO.  Ignore any trailing messages that are
	 * shorter than the minimum.
	 */

	if (buflen % 5 == 0) {
		msglen = 5;
	} else if (buflen % 4 == 0) {
		msglen = 4;
	} else if (buflen % 3 == 0) {
		msglen = 3;
	} else if (buflen % 2 == 0) {
		msglen = 2;
	} else if (buflen == 1) {
		msglen = 1;
	} else {
		msglen = 5;
	}

	while ((buflen - nsent) >= msglen) {
		/* Check if adding this new message would over-run the drivers ability to enqueue
		 * xmit data.
		 */

		nexttail = fifo->af_tail + 1;
		if (nexttail >= CONFIG_DAC_FIFOSIZE) {
			nexttail = 0;
		}

		/* If the XMIT fifo becomes full, then wait for space to become available */

		while (nexttail == fifo->af_head) {
			/* The transmit FIFO is full  -- was non-blocking mode selected? */

			if (filep->f_oflags & O_NONBLOCK) {
				if (nsent == 0) {
					ret = -EAGAIN;
				} else {
					ret = nsent;
				}

				goto return_with_irqdisabled;
			}

			/* If the FIFO was empty when we started, then we will have
			 * start the XMIT sequence to clear the FIFO.
			 */

			if (empty) {
				dac_xmit(dev);
			}

			/* Wait for a message to be sent */

			do {
				ret = sem_wait(&fifo->af_sem);
				if (ret < 0 && errno != EINTR) {
					ret = -errno;
					goto return_with_irqdisabled;
				}
			} while (ret < 0);

			/* Re-check the FIFO state */

			empty = (fifo->af_head == fifo->af_tail);
		}

		/* We get here if there is space at the end of the FIFO.  Add the new
		 * CAN message at the tail of the FIFO.
		 */

		if (msglen == 5) {
			msg = (FAR struct dac_msg_s *)&buffer[nsent];
			memcpy(&fifo->af_buffer[fifo->af_tail], msg, msglen);
		} else if (msglen == 4) {
			fifo->af_buffer[fifo->af_tail].am_channel = buffer[nsent];
			fifo->af_buffer[fifo->af_tail].am_data = *(uint32_t *)&buffer[nsent];
			fifo->af_buffer[fifo->af_tail].am_data &= 0xffffff00;
		} else if (msglen == 3) {
			fifo->af_buffer[fifo->af_tail].am_channel = buffer[nsent];
			fifo->af_buffer[fifo->af_tail].am_data = (*(uint16_t *)&buffer[nsent + 1]);
			fifo->af_buffer[fifo->af_tail].am_data <<= 16;
		} else if (msglen == 2) {
			fifo->af_buffer[fifo->af_tail].am_channel = 0;
			fifo->af_buffer[fifo->af_tail].am_data = (*(uint16_t *)&buffer[nsent]);
			fifo->af_buffer[fifo->af_tail].am_data <<= 16;
		} else if (msglen == 1) {
			fifo->af_buffer[fifo->af_tail].am_channel = 0;
			fifo->af_buffer[fifo->af_tail].am_data = buffer[nsent];
			fifo->af_buffer[fifo->af_tail].am_data <<= 24;
		}

		/* Increment the tail of the circular buffer */

		fifo->af_tail = nexttail;

		/* Increment the number of bytes that were sent */

		nsent += msglen;
	}

	/* We get here after all messages have been added to the FIFO.  Check if
	 * we need to kick of the XMIT sequence.
	 */

	if (empty) {
		dac_xmit(dev);
	}

	/* Return the number of bytes that were sent */

	ret = nsent;

return_with_irqdisabled:
	irqrestore(flags);
	return ret;
}

/************************************************************************************
 * Name: dac_ioctl
 ************************************************************************************/

static int dac_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct dac_dev_s *dev = inode->i_private;
	int ret;

	ret = dev->ad_ops->ao_ioctl(dev, cmd, arg);
	return ret;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/************************************************************************************
 * Name: dac_txdone
 *
 * Description:
 *   Called from the DAC interrupt handler at the completion of a send operation.
 *
 * Return:
 *   OK on success; a negated errno on failure.
 *
 ************************************************************************************/

int dac_txdone(FAR struct dac_dev_s *dev)
{
	int ret = -ENOENT;

	/* Verify that the xmit FIFO is not empty */

	if (dev->ad_xmit.af_head != dev->ad_xmit.af_tail) {
		/* Remove the message at the head of the xmit FIFO */

		if (++dev->ad_xmit.af_head >= CONFIG_DAC_FIFOSIZE) {
			dev->ad_xmit.af_head = 0;
		}

		/* Send the next message in the FIFO */

		ret = dac_xmit(dev);
		if (ret == OK) {
			/* Inform any waiting threads that new xmit space is available */

			ret = sem_post(&dev->ad_xmit.af_sem);
		}
	}

	return ret;
}

int dac_register(FAR const char *path, FAR struct dac_dev_s *dev)
{
	/* Initialize the DAC device structure */

	dev->ad_ocount = 0;

	/* Initialize semaphores */
	sem_init(&dev->ad_xmit.af_sem, 0, 0);
	sem_init(&dev->ad_closesem, 0, 1);

	/*
	 * The transmit semaphore is used for signaling and, hence, should
	 * not have priority inheritance enabled.
	 */
	sem_setprotocol(&dev->ad_xmit.af_sem, SEM_PRIO_NONE);

	dev->ad_ops->ao_reset(dev);

	return register_driver(path, &dac_fops, 0555, dev);
}
